There are many causes of hearing impairments, particularly common causes include the history of exposure to loud noises (including music) of a large portion of the population, and presbyacousis (the decline of hearing with age). These, combined with the increasing average age of people in the United States and Europe, is causing the population of hearing-impaired to soar.
Oral communication is fundamental to our society. Hearing-impaired people frequently have difficulties understanding oral communication; most hearing-impaired people consider this communication difficulty the most serious consequence of their hearing impairment. Many hearing-impaired people wear and use hearing prosthetics, including hearing aids or cochlear implants and associated electronics, to help them understand other's speech, and thus to communicate more effectively. They often, however, still have difficulty understanding speech, particularly when there are multiple speakers in a room, or when there are background noises. It is expected that reducing background noise, including suppressing speech sounds from people other than those a wearer is interested in communicating with, will help these people communicate.
While many hearing-aids are omnidirectional—receiving audio from all directions equally, directional hearing-aids are known. Directional hearing-aids typically have a directional microphone that can be aimed in a particular direction; for example a user can aim a directional wand at a speaker of interest to him, or can turn his head to aim a directional microphone attached to his head, such as a microphone in a hearing-aid, at a speaker of interest. Other hearing-aids have a short-range radio receiver, and the wearer can hand a microphone with short-range radio transmitter to the speaker of interest. Some users report improved ability to communicate with such devices that reduce ambient noises.
Some systems described in the prior art have the ability to adapt their behavior according to changes in the acoustic environment. For example, a device might perform in one way if it perceives that the user is in a noisy restaurant, and might perform in a different way if it perceives that the user is in a lecture hall. However typical prior devices response to an acoustic environment might be inappropriate for the specific user or for the user's current preferences.
Other prior devices include methods to activate or deactivate processing, depending on the user's cognitive load. These methods represent some form of neural feedback control from the user to the hearing device. However, the control is coarse, indeed binary, with enhancement either on or off. Further, prior devices known to the inventors do not enhance the performance of the processing in producing a more intelligible version of the input sound for the user.